AWS Amplify
Console User Guide

Configuring Build Settings

The Amplify Console automatically detects the front end framework and associated build settings by inspecting the package.json file in your repository. You have the following options:

  • Save the build settings in the Amplify Console - The Amplify Console autodetects build settings and saves it so that they can be accessed via the Amplify Console. These settings are applied to all of your branches unless there is a YML file found in your repository.

  • Save the build settings in your repository - Download the amplify.yml file and add it to the root of your repository (or root of the app folder for monorepos).

You can edit these settings in the Amplify Console by choosing App Settings>Build settings. These build settings are applied to all the branches in your app, except for the branches that have a YML file saved in the repository.

YML Specification Syntax

The build specification YML contains a collection of build commands and related settings that the Amplify Console uses to run your build. The YML is structured as follows:

version: 1.0 env: variables: key: value backend: phases: preBuild: commands: - *enter command* build: commands: - *enter command* postBuild: commands: - *enter command* frontend: phases: preBuild: commands: - cd react-app - npm ci build: commands: - npm run build artifacts: files: - location - location discard-paths: yes baseDirectory: location cache: paths: - path - path customHeaders: - pattern: 'file-pattern' headers: - key: 'custom-header-name' value: 'custom-header-value' - key: 'custom-header-name' value: 'custom-header-value' test: phases: preTest: commands: - *enter command* test: commands: - *enter command* postTest: commands: - *enter command* artifacts: files: - location - location configFilePath: *location* baseDirectory: *location*
  • version - Represents the Amplify Console YML version number.

  • env - Add environment variables to this section. You can also add environment variables using the console.

  • backend - Run Amplify CLI commands to provision a backend, update Lambda functions, or GraphQL schemas as part of continuous deployment. Learn how to deploy a backend with your frontend.

  • frontend - Run frontend build commands.

  • test - Run commands during a test phase. Learn how to add tests to your app.

  • The frontend, backend, and test have three phases that represent the commands run during each sequence of the build.
    • preBuild - The preBuild script runs before the actual build starts, but after we have installed dependencies.

    • build - Your build commands.

    • postBuild - The post-build script runs after the build has finished and we have copied all the necessary artifacts to the output directory.

  • artifacts>base-directory - The directory in which your build artifacts exist.

  • artifacts>files - Specify files from your artifact you want to deploy. **/* is to include all files.

  • customHeaders - Custom header rules set on deployed files. See custom headers.

Branch-Specific Build Settings

You can use bash shell scripting to set branch-specific build settings. For example, the following script uses the system environment variable $AWS_BRANCH to execute one set of commands if the branch name is master and a different set of commands if the branch name is dev.

frontend: phases: build: commands: - if [ "${AWS_BRANCH}" = "master" ]; then echo "master branch"; fi - if [ "${AWS_BRANCH}" = "dev" ]; then echo "dev branch"; fi

For monorepos, users want to be able to cd into a folder to run the build. After you run the cd command, it applies to all stages of your build so you don't need to repeat the command in separate phases.

version: 1.0 env: variables: key: value frontend: phases: preBuild: commands: - cd react-app - npm ci build: commands: - npm run build

Deploying the Backend with Your Front End

The amplifyPush is a helper script that helps you with backend deployments. The build settings below automatically determine the correct backend environment to deploy for the current branch.

version: 1.0 env: variables: key: value backend: phases: build: commands: - amplifyPush --simple

Setting the Output Folder

The following build settings set the output directory to the public folder.

frontend: phases: commands: build: - yarn run build artifacts: baseDirectory: public

Installing Packages as Part of Your Build

You can use npm or yarn to install packages during the build.

frontend: phases: build: commands: - npm install -g pkg-foo - pkg-foo deploy - yarn run build artifacts: baseDirectory: public

Using a Private npm Registry

You can add references to a private registry in your build settings or add it as an environment variable.

build: phases: preBuild: commands: - npm config set <key> <value> - npm config set registry - npm config set always-auth true - npm config set email - yarn install

Installing OS packages

You can install OS packages for missing dependencies.

build: phases: preBuild: commands: - yum install -y <package>

Key-value storage for every build

The envCache provides key-value storage at build time. Values stored in the envCache can only be modified during a build and can be re-used at the next build. Using the envCache, we can store information on the deployed environment and make it available to the build container in successive builds. Unlike values stored in the envCache, changes to environment variables during a build are not persisted to future builds.

Example usage:

envCache --set <key> <value> envCache --get <key>

Disable Automatic builds

You can configure Amplify Console to disable automatic builds on every code commit. To set up, choose App settings > General and then scroll to the section with all the connected branches. Select a branch, and then choose Action > Disable auto build. Further commits to that branch will no longer trigger a new build.